ThinkSecret has posted some initial information about Apple's Intel-based Mac development kits that recently started shipping to developers.

The Apple Development Platform ADP2,1, as the systems are officially designated, features 3.6GHz Pentium 4 processors with 2MB of L2 cache operating on an 800MHz bus with 1GB of RAM.
The Intel-based systems can run Mac OS X 10.4 'Tiger' without a hitch, as is to be expected, but more interesting is that the kits could also run Windows XP from a NTFS-formatted partition.

As for installing Mac OS X on non-Apple hardware, attempts to boot from the included Mac OS X for Intel disc resulted in an error message on both a Dell and off-brand PC. The message states that the hardware configuration is not supported by Darwin x86.